In an inserting machine for mass mailing, there is a gathering section where enclosure material is gathered before it is inserted into an envelope. This gathering section is sometimes referred to as a chassis subsystem, which includes a gathering transport with pusher fingers rigidly attached to a conveyor belt and a plurality of enclosure feeders mounted above the transport. If the enclosure material contains many documents, these documents must be separately fed from different enclosure feeders. After all the released documents are gathered, they are put into a stack to be inserted into an envelope in an inserting station. Envelopes are separately fed to the inserting station one at a time, and each envelope is placed on a platform facing down with its flap flipped back all the way. Typically, mechanical fingers or vacuum suction devices are used to keep the front side of the envelope on the platform while the throat on the back side of the envelope is pulled upward to open the envelope. The stack of enclosure material is than automatically inserted into the opened envelope.
In the past, vacuum suction has been used to open envelopes as a precursor to material insertions. For example, U.S. Pat. No. 5,052,168 (DeWitt el al.) discloses a method and an apparatus to spread open an envelope where two suction cups are placed on the opposing faces of the envelope. An air flow is drawn through two respective suction arms to produce a negative air pressure in order to spread out the envelope faces. A vacuum pump, along with a plurality of bleed valves, release valves and dump valves is used to produce the necessary suction force. Like other similar designs, the method disclosed by DeWitt et al. uses a constantly running vacuum pump to draw the air flow in order to open and maintain the open position of envelopes for either material insertion or extraction. The various valves in the vacuum manifold are opened or closed whenever vacuum is required for the suction cups to pick up the faces of the envelope. Typically, a large A.C. vacuum pump is required to produce the necessary suction force. The disadvantages of using such a vacuum pump in an inserting machine include the following:
1) a large housing is required to accommodate such a vacuum pump; PA1 2) energy is wasteful because the power consumption of a large pump is high; PA1 3) energy is wasteful because the pump is kept running even when it is not used to open an envelope; and PA1 4) the noise levels generated by the constantly running pump are high.
It is advantageous to provide a method and an apparatus for opening envelopes in a document insertion and extraction station, wherein the apparatus is activated only during the period that it is needed to open an envelope and the apparatus permits the use of a small motor and eliminates the need for external valving to control the vacuum.